Blog SEO: Tag blog posts with long-tail vs. short-tail keywords?

[flip]

Hello,

I am wondering which blog post tagging strategy is recommendable regarding the tag pages which are auto-generated by most blog systems such as WordPress or Ghost: Using long-tail vs. short-tail keywords?

Long-Tail:

• mac vpn -> example.com/tag/mac-vpn
• mac firewall -> example.com/tag/mac-firewall

Short-Tail:

• mac -> example.com/tag/mac
• vpn -> example.com/tag/vpn
• firewall -> example.com/tag/firewall

My assumption would be that long-tail keywords for blog post tagging would be better:

• Better chance to rank on SERPs for these keywords via auto-generated tag pages
• Much more relevant traffic from auto-generated tag pages

However, most often I see that blog posts are tagged with short-tail keywords (blog / seo) vs. long-tail keywords (blog seo). Even when using short-tail keywords, would you even have a chance to rank for a relevant long-tail keyword such as "blog seo" rather than attracting very broad traffic via the terms "seo" and "blog".

I am not talking about optimizing and ranking the blog post itself but using the auto-generated tag pages from a blog to attract relevant SEO traffic.

Thanks,

Philip